Kano Ienaga

Ienaga is one of the 24 Abashiri convicts who had the map leading to the Ainu treasure tattooed onto their skins by Noppera-bou. Ienaga has always loved art for a long time and has extensive medical knowledge. Her previous name was Chikanobu.

[Spoiler] In flashbacks to the Abashiri prison she is shown, and mentioned, as a old male doctor. When Sugimoto's group first meet her at her murder hotel, it's revealed she murders her victims and consumes their desirable parts to keep her youth. She practiced a Chinese healing diet in which one eats a part of the body where one is ill, except she did this with her human patients. [/Spoiler]

(Source: Golden Kamuy Wikia)